Poland's Holocaust law should terrify you
https://edition.cnn.com/2018/02/06/opinions/poland-holocaust-denial-opinion-ghitis/index.html
The most important thing is not finding out who was responsible for the massacre and blaming them, but conveying tragic history to younger generations in order not to repeat the same history.
Polish decision seems to be afraid of the former movement. Nazi victims would also have to pay attention to horror of being treated as Nazi supporters.